It’s got all the ingredients of a high-stakes courtroom thriller: billions of dollars on the line, intense Wall Street deal-making, and highly profitable oil speculation. But the big banks aren’t taking any chances in this drama. They’ve hired the son of Supreme Court justice Antonin Scalia to help them fight regulations which might crimp their profits.

In one of the highest-profile challenges to the sweeping Dodd-Frank financial industry overhaul, two financial industry groups sued the Commodity Futures Trading Commission in federal court to toss a rule that limits speculation by banks.